First came the shock and the grief. Four Canadian soldiers were killed and eight more wounded last week in Afghanistan, the first Canadian casualties in a combat zone since the Korean war.

Then came the anger. The four young men died when a US F-16 fighter pilot mistakenly dropped a 500-pound laser-guided bomb on them while they took part in a night time training operation.

The tragedy, devastating for the families involved, has also created a potentially difficult political situation for the government. After September 11, the prime minister, Jean Chretien, was eager to prove he was serious about the fight against terrorism. He chose to send soldiers as part of the US military operation in Afghanistan rather than accept a small role that had been offered as part of the multinational peacekeeping force led by Great Britain.

The accident was obviously the result of a breakdown in communication and raises serious questions about whether 750 Canadian soldiers have been properly integrated into the US mission. In the eyes of many Canadians, it also raises questions about whether the US is indifferent to foreign troops who have joined its fight against terrorism.

"The symbolism, for those who think we have no business being in Afghanistan, is too rich to miss. We went to help out the Americans with their war - and they used us for target practice," said a front-page column in The Globe and Mail, one of Canada's national newspapers.

The situation was made worse when a seemingly indifferent US President, George Bush, failed to offer condolences during the five public appearances he made on the day after the Canadians were killed. At one event, he brushed off a shouted question from a Canadian reporter as he hurried out the door. The next day, after criticism from Canada's deputy prime minister, Mr Bush took a few minutes to say the words Canadians were waiting to hear.

"I want to say publicly what I told Jean Chretien the other day about how sorry I am that Canadian soldiers lost their lives in Afghanistan. It was a terrible accident."

Wars are dangerous, and the risk of dying from so-called "friendly fire" is high, a fact of life for the US commander in chief. One quarter of all the fatalities in the Gulf War were accidents. But Canadians, who are accustomed to sending soldiers to peace-keeping operations, are unused to the realities of modern combat.

Many callers to radio phone-in shows and media internet sites said Canada was paying too high a price for its support of the US war on terrorism. Four panels in both Canada and the United States are now investigating the accident.

Canada's Chief of Defence Staff, General Ray Henault, says the soldiers were in a recognised training area near the Kandahar airbase and that US authorities were aware of their night time exercise, which involved live ammunition. Yet the pilot of the F-16 believed he was under attack when he flew over the area, and decided to drop the bomb.

Canadians have largely been supportive of the government's decision to send troops to Afghanistan, but pollsters warn that could change quickly if there are more casualties and if the US does not move quickly to explain why the pilot of the F-16 dropped his bomb.

Mr Chretien told the Commons that Canada has no intention of pulling its forces out of the Afghanistan campaign as a result of the accident. He looked troubled as he offered condolences to the families and friends of the four victims, who are members of the Princess Patricia's Light Infantry.

"At times like these, we grasp for words of comfort and consolation. But they are just words. They can never do justice to the pain and loss... being felt by mothers and fathers, wives and children."

Opposition parties, however, did not attack Mr Chretien or attempt to capitalise on the difficult situation in which he finds himself. Leaders of both the Canadian Alliance and the separatist Bloc Quebecois crossed the floor of the Commons to shake Mr Chretien's hand and offer their personal support.

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